1. Field of the Invention
The present invention relates to flame-resistant moulding compositions of polycarbonates and graft polymers which, in addition to good flow properties, have very good mechanical properties and a particularly good, trouble-free surface. These moulding compositions are suitable in particular for injection moulding uses for mouldings with thin wall thicknesses and high-gloss surfaces.
2. Description of Related Art
EP 0 363 608 describes polymer mixtures of aromatic polycarbonate, styrene-containing copolymer or graft copolymer and oligomeric phosphates as flameproofing additives. For certain fields of use, the level of mechanical properties, in particular the weld strength, the flow properties and in particular the surface quality, is not adequate.
EP 0 704 488 describes moulding compositions of aromatic polycarbonate, styrene-containing copolymers and graft polymers with a specific graft base in certain ratios of amounts. These moulding compositions can optionally be rendered flame-resistant with phosphorus compounds. These moulding compositions have very good notched impact strengths, although the flow properties and surface quality are not adequate for certain intended uses.
EP 747 424 describes thermoplastic resins which contain phosphate compounds with a molecular weight of from 500 to 2,000 and phosphate compounds with a molecular weight of from 2,300 to 11,000 as flameproofing agents, a large number of thermoplastic resins being listed. The flow properties of the moulding compositions are impaired significantly by the high molecular weights of the phosphorus compounds.
EP 754 531 describes reinforced PC/ABS moulding compositions which are suitable for precision parts. Inter alia, oligophosphates of the BPA types are also used as flameproofing agents. The high filler contents have a very adverse effect on the mechanical properties and the flow properties.
EP 755 977 describes polymer mixtures of aromatic polycarbonate, graft copolymer with a rubber content of <25% and oligomeric phosphates with a content of <8%. Due to the limited flameproofing agent content, the flow properties and the flame resistance are not adequate. Moreover, there are no indications of the desired good surface quality.
EP 1 003 809 describes PC/ABS moulding compositions which contain oligomeric phosphorus compounds and graft polymers of a graft base with a certain particle size. These moulding compositions are distinguished by good mechanical properties, in particular also under increased elasticity stress. However, their flow properties, their flame resistance and their surface quality are not adequate for certain fields of use.
EP 0 983 315 describes moulding compositions of aromatic polycarbonate, graft polymer and a flameproofing agent combination of a monomeric and an oligomeric phosphorus compound. These moulding compositions have a high heat distortion temperature and excellent mechanical properties (notched impact strength and weld line strength), although the flow properties and the flame resistance, in particular in shaped articles with thin wall thicknesses, is not adequate.
EP 1 165 680 describes flame-resistant PC/ABS moulding compositions with good mechanical properties (tensile strength, weld line strength), which contain oligomeric phosphates with a defined chain length. The ranges of amounts chosen for flameproofing agents and graft polymer are very wide. The property combination according to the invention of flow properties, good mechanical properties and good surface quality is therefore not described.